Lubricating oil composition



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i] t d St t I 3,014,869 I LUBRICATING ()IL CONHOSITIQN William W. Reynolds and Hans Low, East Alton, 'Iil assignors to ShellOil Company, a corporation of Delawere No Drawing. tutu news, 1959', Ser. No. 349,453

- 2 Claims. ((1252- 196) 7 r This invention relates-to improved lubricating oil compositions, and more particularly to mineral lubricating oil compositions which are resistantto oxidative deterioraatent tion under storage or use in equipment subjected to adverse operating conditions of temperature and pressure. Lubricating oils such as mineraloils in the lubricating viscosity range tend to deteriorate and break down due to oxidation both in storage and during use, particularly at extremely high temperatures, such as above 400 F. and higher, resulting in the formation of undesirable products such as gums, sludges, resins, acidic products and other I deleterious products which decrease the useful life of the oil or render it useless within a short period of time. Mineral oils of this type include aircraft, truck and automobile mineral lubricating oils, industrial oils such as gear oils, transformer oils, hydraulic oils and the like.

It is known that certain aromatic amines are useful as oxidation inhibitors for 'mineral oils. However, their application is limited because of their tendency to discolor mineral oils and form deposits, particularly at or prevent deterioration, discoloration and deposit formation in mineral oil during storage and use over a wide temperature range, particularly at elevated temperatures. Other objects of the invention will be apparent from the following description of the invention.

Specific gravity 0.876 Pour point, F. +10 Viscosity at 100 F., cs 56.88 V.I 93.9 Flash point, COC, F 450 Fire point, F 490 Aromatics, percent 23.7

It has now been discovered that various types of mineral lubricating oil including those which contain substantial amounts of aromatics (530%) can be effectively stabilized even at temperatures above 400 F. without undesirable side effects by addition 'thcreto of small amounts (0.054%, preferably 0.11% by weight.) each of an oil-soluble aromatic amine having the Formula I RR NH, wherein the Rs are the same or different monoor diaromatic radicals, and an oil-soluble boron ester having the Formula II (RO) B, wherein R is an alicyclic group, preferably monocyclic group of non-aromatic carbyl radicals, or polar radicals such as halogenihydroxyl, amino, nitro, or carboxylate radicals. Boron esters represented .by Formula. II in which at least one and preferably two Rs of cyclohexyl groups are preferred.

The, oil-soluble aromatic "amines represented by Formula I includeldiphenyl, dinaphthyl, phenyl alphanaphthyl, phenyl beta-naphthyl amines and mixtures thereof.

' character which may contain substituent C C hydro- The tricycloalkyl borates represented by Formula II 1 (RO) B- are prepared by any suitable'means such as by reacting under reflux conditions boric acid with a desired cycloalkanol in a suitable solvent such as a liquid hydrocarbon, e.g., benzene, toluene or the like;

Suitable alicyclic alcohols for use as starting materials in the preparation of compounds of this invention'include cycloalkanols, such as cycloperitanols, cyclopentenols,

heptanols', etc, Representative specific compounds are 3,3,5 trimethylcyclohexanol, 4,6 4 diter tiarybutyl 2 methyl-cyclohexanol, borneol, isoborneol, abietyl alcohol,

cyclohexanols, cycloheptanols, cycloheptenols, bicyclo air flow of 1 liter/hour oxidizing agent, 400 F.,

cycloalkanols produced by hydrogenation of isophorone and isophorone bottoms as described in Adelson U. S. Patents 2,481,487 and 2,502,408 as well as cycloalkenols described in US. Patents 2,433,008, 2,467,451, 2,493,733, 2,497,349, 2,574,077 and 2,597,843.

Specific representative cycloalkyl borates useful in lubricating compositions of the present invention, are tricyclohexyl borate, tri(3,3,S-triethylcyclohexyl)borate, tri(4,6'- ditertbutyl 3 methylcyclohexyl)borate, tri(2- cyclohexylcyclohexyl)borate, tri(2 phenylcyclohexyl)- borate, tri(2 chlorocyclohexyl)borate, phenyl dicyclohexyl borate, tri(2,3 dimethylcyclopentyl)borate, tri(2- butylcycloheptyl)borate, dicyclohexylcyclopentyl borate and the like.

The additive combination of this invention effectively stabilizes a variety of petroleum lubricating stocks such as parafiinic, naphthenic and mixed base mineral oils having a viscosity range of from 50 SUS at F. to 250 SUS at 210 F. A typical useful oil is a refined mineral lubricating oil (X) having the following properties:

Pour point, F 29-31 Flash point, F. (COC) Min. 420 Viscosity SUS, 100 F 345-355 Unsulfonated residue Min. 98

Another typical useful oil (Y) is an Oklahoma neutral petroleum fraction having the following properties:

To illustrate the pronounced superiority of the additive combination in stabilizing and preventing oxidation of mineral oil, the following compositions were prepared and evaluated in a micro-oxidation test of the MIL-L- 7808 oxidation test under the following testcondition: solid metal catalyst (Ag, Ti, Cu, Mg, Fe), with the results as shown in Table I.

Table I [Eraser-refined mineral lubricating oil X,'amou11t 0t Inhibitor=0.02 M'=0.002 mole/100 g.]

Other compositions of this invention which would be expected to give comparable results to composition 6, Table I of this invention, include:

(7) Mineral oil+0.02 M phenylalpha-naphthylamine +0.02 M tri(3,3,5-triethy1 cyclohexyl)borate,

(8) 'Mineral oil+0.02 M phenyl-alpha-naphthylarnine +0.02 M tri(4,6-ditertbutyl-3methyl cyclohexyl)borate,

(9) Mineral oil}0.02 M beta,beta-dinaphthylamine+0.02 M tricyclohexyl borate, I t (10.) lvfineral oil+0.05 M phenyl-alpha-naphthylamine +0.03 M tri(Z-butylcy'ciloheptyl)borate.

' PatentedDec. 2c, 1961 sentially of a major amount of mineral lubricating oil and from about 0.05% to about 2% each, of (1) an oilsoluble aromatic amine selected from the group consisting of phenyl-alpha-naphthylamine and beta-beta-dinaphthylamine and (2) an oil-soluble cycloalkyl borate selected from the group consisting of tri(cyclohexyl)borate, tri- (3,3,5 triethyl cyclohexyDborate, tri(4,6 ditertbutyl 3- methyl cyclohexyl)borate, and tri(2-butylcycloheptyl)- borate.

2. A mineral lubricating oil containing from about 0.05% to about 2% each of phenyl-alpha-naphthylamine and tricyclohexyl borate.

References Cited in the file of this patent UNITED STATES PATENTS 2,084,472 Wiezevich June 22, 1937 2,160,917 Shoemaker et a1 June 6, 1939 2,312,208 Clayton et al. Feb. 26, 1943 2,452,319 Patterson et a1 Oct. 26, 1948 2,721,181 Lawrence et al. Oct. 18, 1955 FOREIGN PATENTS 748.430 Great Britain May 2, 1956 

1. A MINERAL LUBRICATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF MINERAL LUBRICATING OIL AND FROM ABOUT 0.05% TO ABOUT 2% EACH, OF (1) AN OILSOLUBLE AROMATIC AMINE SELECTED FROM THE GROUP CONSISTING OF PHENYL-ALPHA-NAPHTHYLAMINE AND BETA-BETA-DINAPHTHYLAMINE AND (2) AN OIL-SOLUBLE CYCLOALKYL BORATE SELECTED FROM THE GROUP CONSISTING OF TRI(CYCLOHEXYL)BORATE, TRI(3,3,5-TRIETHYL CYCLOHEXYL)BORATE, TRIL(4,6-DITERBUTYL - 3METHYL CYCLOHEXYL)BORATE, AND TRI(2-BUTYLCLOHEPTYL)BORATE. 